/*! ========================================================================
** Extended Template and Library
** Utility Curve Template Class Implementations
**
** Copyright (c) 2002 Robert B. Quattlebaum Jr.
**
** This package is free software; you can redistribute it and/or
** modify it under the terms of the GNU General Public License as
** published by the Free Software Foundation; either version 2 of
** the License, or (at your option) any later version.
**
** This package is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
** General Public License for more details.
**
** === N O T E S ===========================================================
**
** This is an internal header file, included by other ETL headers.
** You should not attempt to use it directly.
**
** ========================================================================= */

#ifndef __ETL__CURVE_FUNC_H
#define __ETL__CURVE_FUNC_H

#include <functional>
#include "_fixed.h"

template <class T, class K = float>
struct affine_combo {
    T operator()(const T &a, const T &b, const K &t)const
    {
        return T((b - a) * t + a);
    }

    T reverse(const T &x, const T &b, const K &t)const
    {
        return T((x - t * b) * (static_cast<K>(1) / (static_cast<K>(1) - t)));
    }
};

template <class T, class K = float>
struct distance_func : public std::binary_function<T, T, K> {
    K operator()(const T &a, const T &b)const
    {
        T delta = b - a;
        return static_cast<K>(delta * delta);
    }

    K cook(const K &x)const
    {
        return x * x;
    }
    K uncook(const K &x)const
    {
        return sqrt(x);
    }

};

#endif